In planning my next plant wall I’ve been testing hydroponic planting medium. In the past I’ve used hydroton but there are currently two issues with this media. Because it’s heavy in iron it eventually trashes the magnetic pump. I replace pumps about once a year. At about $50 a pop that’s not horribly expensive but it is inconvenient. Secondly, it’s no longer available. That makes the inherent equipment-related problems with the media moot.
I bought two bags of a product that was supposed to be a replacement for hydroton. It felt like sandpaper, very garnet/scratchy expanded glass feeling. The pieces were quite large for hydroponic media, didn’t break when whacked with a hammer and very light. Other than the roughness and overly large size, I thought it would work fine. Wrong. The stuff floats. Using it in a flood and drain system allows all the plantings to shift every watering cycle. When working with seeds, the media used to hold the seeds vanishes into the mix. Ugh. When planting cuttings they sink a bit into the mix every cycle eventually drowning. Double ugh.
I reported the failure to the excellent staff at our local hydroponic shop and got a sample of another product to try. It had a light silky clay feel, sank when dropped into water and could be crushed. The product is a little big, roughly 2-3 times the size of the hydroton beads.
PH is one of the most important items to monitor in a hydroponic system. I’m not a fan of chemicals and like to handle this as naturally as possible which makes the ph of the media very important. With that in mind I crushed a piece of the new media and tested the ph. It tested lower than I expected at 6.0 which means it’s not inert. Because our water has a very low ph which I moderate with oyster shell, I’m keeping an eye on my test system. Time will tell.